The invention relates to an improved process for hydration of acrylonitrile to acrylamide where oxazole is excluded from the reactant feed streams, acrylonitrile and water. The acrylamide produced in this improved hydration process exhibits exceptionally improved stability and low content of soluble and insoluble polymeric impurities without need for posthydration treatment such as that described in U.S. Pat. No. 3,923,741 or Japanese Pat. Nos. Kokais 113,913 (1977); 116,410 (1977); 83,323 (1975); and 82011 (1975). Acrylamide polymers prepared by the polymerization of acrylamide monomer from the improved process exhibit higher viscosity in aqueous solution than polymers prepared from acrylamide produced from acrylonitrile containing substantial oxazole.
The removal of oxazole from acrylonitrile is taught in U.S. Pat. Nos. 3,541,687 and 3,574,687 by contacting the acrylonitrile with a water-moist cation exchange resin in the hydrogen form. Regeneration is accomplished with deionized water or steam. It is suggested in U.K. Pat. No. 1,131,134 that oxazole may be removed from acrylonitrile by hydroextractive distillation. It has also been taught in U.S. Pat. No. 3,146,258 and other patents that methylvinyl ketone impurity is removed from acrylonitrile by contacting with a strong acid cation exchange resin in its hydrogen form previously treated with a lower alkanol. In U.S. Pat. No. 2,444,589 an ion exchange material in conjunction with a decolorizing agent such as charcoal is utilized to purify acrylonitrile. The resultant purified acrylonitrile may be utilized in the preparation of acrylonitrile polymers to avoid discoloration of the ultimate product and therefore enhance the desirability of fibers or other colorless plastic articles prepared from such polymers. Acrylonitrile supplied commercially for heterogeneous catalytic production of acrylamide has commonly contained about 200 to 300 ppm (by weight) of oxazole, based on acrylonitrile.